The US State Department has expressed its disappointment at the decision by Google's chairman to travel to North Korea.

But former New Mexico governor Bill Richardson, who will travel to the secretive state with Eric Schmidt, said the State Department should not be nervous.

Mr Richardson, who has been involved in unofficial negotiations with North Korea since 1994, has told the CBS show "This Morning" that it is a private, humanitarian mission.

The State Department has said it will have no involvement in the visit, which is expected to take place in the next month.

"Frankly, we don't think the timing of this is particularly helpful, but they are private citizens and they are making their own decisions," spokeswoman Victoria Nuland said in Washington.

"They are travelling in an unofficial capacity they are not going to be accompanied by any US officials. They are not carrying any messages from us," she added.

The purpose of this visit has not been disclosed. North Korea is seen as the last frontier of the internet, leading to speculation that this is a strategic and business-related move for Google.

Kim Jong-Un has called for an end to confrontation with the South

The few who do have access to a computer in North Korea do not have access to the World Wide Web and instead use a heavily censored intranet service.

A Google spokesperson said it would not comment on Mr Schmidt's "personal travel".

The US State Department has, in the past, encouraged the use of the internet to spread democracy.

However, this visit is seen as "unhelpful" because of its timing, coming just weeks after Pyongyang successfully launched a rocket into orbit. The launch was, America says, a cover for a ballistic missile test.

There is some speculation that Mr Schmidt and Mr Richardson may attempt to negotiate the release of Korean-American Kenneth Bae.

Mr Richardson said he is concerned about the case and that he has spoken to Mr Bae's son.

Mr Bae was arrested by the North Korean authorities in mid-December. According to South Korean media, he was with five other tourists when he was accused of being a spy and detained.

On Monday, the North Korean leader, Kim Jong-Un delivered an unprecedented televised address to the nation in which he called for an end to confrontation with the South.

He said the country would undergo a "radical turnaround" becoming an "economic giant". Quite how this would be achieved was not outlined.